The common differential consists of planetary gears, planetary carrier (differential housing), and semi-axle gears. The power of the engine enters the differential through the transmission shaft, directly drives the planetary carrier, and then the left and right axles are driven by the planetary wheels to drive the left and right wheels respectively. The differential design requirements are: (left half shaft speed) + (right half shaft speed) = 2 (plane wheel speed). When the car goes straight, the rotational speeds of the left and right wheels and the planetary carrier are equal, and the balance state of the three is destroyed when the car turns, resulting in a decrease in the inner wheel speed and an increase in the outer wheel speed.